Conventional apparatuses employed in medical x-ray imaging which are most simple as for their basic structure comprise a source of radiation which is used together with a film cassette separate from the source of radiation. Hospitals commonly also use so-called C-arch x-ray apparatuses in which the source of radiation and the receiver of image information are arranged at the opposite ends of the arch-shaped arm part. Conventionally, a group of apparatus completely of its own consists of large-size and extremely expensive computed tomography apparatus, into which a patient is typically positioned for imaging in a lying position inside a ring-shaped or tubular structure.
As conventional computed tomography apparatus have been quite massive and expensive, acquiring them e.g. for the use of hospital emergency rooms has not been possible in practice. On the other hand, it has also been typical for commercial computed tomography apparatus that they are not necessarily designed for imaging some specific anatomy or anatomies but they are more or less general imaging apparatus. If one wishes to image e.g. the patient's whole torso, the imaging station arranged to the apparatus as well as other dimensions of the apparatus must have been implemented in respective proportions.
More lightweight computed tomography apparatus versions have been developed as well. As an example of prior art solutions, a reference can be made to a structure disclosed e.g. in the WO publication 2011/135186. In such apparatus, imaging means arranged to move around an imaging station are arranged within a ring-shaped O-arm, supported from its side.
In the more lightweight apparatus according to the prior art as referred to above cone beam tomography KIM may be used. There, one criterion which limits the size of a volume getting imaged (FOV—Field of View) is the dimensions of the imaging detector, which for obvious reasons cannot be arranged in such context to be very large. When considering imaging an extremity, for example, it is clear that when using such an imaging apparatus it is possible to image only a single partial volume of the extremity by one mutual positioning of the patient and the imaging apparatus. Then it becomes necessary to position the anatomy in the imaging apparatus anew, for imaging the next partial volume, and realizing the re-positioning in relation to the previous positioning in an exactly desired way can be a challenge.